A database system that handles large-scale data such as a data center, for example, manages data by using a storage control system that is constituted separately from a host computer. This storage control system is a disk array system such as a RAID (Redundant Array of Independent Inexpensive Disks) that is constituted by arranging a multiplicity of storage devices in the form of an array, for example.
In step with the advances of an information-driven society, the amount of data to be managed by databases is increasing on a daily basis. For this reason, storage control systems with a higher performance and larger capacity are needed. New storage control systems are being developed to meet market demands. Two methods for introducing new storage control systems as storage systems may be considered. One such method involves completely switching an old storage control system for a new storage control system and constituting a storage system entirely from the new storage control system (Patent Document 1: Japanese Patent Application No. H10-508967). The other method involves combining usage of a new storage control system by newly adding the new storage control system to a storage system comprising the old storage control system.
Further, a technology that manages physical device storage areas in sector units and dynamically constitutes logical devices in sector units is also known (Patent Document 2: Japanese Patent Application Laid Open No. 2001-337850).
When a complete transition is made from an old storage control system to a new storage control system (Japanese Patent Application No. H10-508967), the functions and performance of the new storage control system can be utilized but the old storage control system cannot be effectively used, meaning that the introduction costs also increase. On the other hand, when the old storage control system and the new storage control system are combined, the number of storage control systems constituting the storage system increases and the labor involved in managing and running the new storage control system is large.
Further, when the responsiveness of a storage device that the old storage control system comprises is low, the performance of the whole system drops as a result of connecting the old storage device to the storage system. For example, when the old storage device is a device that involves a mechanical operation (head seek and so forth), there are cases where the mechanical operation time is long and where the data transfer buffer capacity that the old storage device comprises is small.
In addition, there are also cases where an old storage device cannot be utilized as in the case of open-system storage devices and mainframes, and servers that can only connect to storage devices with a specific function.
As one method for resolving this problem, a method that makes it possible to utilize storage resources effectively by allowing co-operation between first and second storage control systems, for example, may be considered.
However, with this method, for example, in a case where the first storage control system receives control system information relating to the second storage control system from the second storage control system, and the control processor (microprocessor, for example) of the first storage control system executes various processing based on the control system information thus received, when the type of the second storage control system (machine type or vendor, and so forth, for example) changes, the microprogram of the control processor of the first storage control system must be changed. This is because, when the machine type or vendor and so forth is different, the position, order, and data size of each information item (vendor ID, device name, and so forth, for example) of the control system information are sometimes different and there is the risk that the microprogram corresponding with a certain type of second storage control system will be unable to handle control system information that is outputted by an external storage control system of another second storage control system type.
Further, with the above method, when the host device is connected to the first storage control system, because the second storage control system cooperates with the first storage control system, there is a problem from the point of view of security when the host device is able to freely access the second storage control system via the first storage control system.
Furthermore, with the above method, in cases where a host device is connected to the first storage control system, when the host device consumes the storage capacity of the second storage control system via the first storage control system, there is the advantage that billing according to the storage capacity consumed is possible while preserving security.